A typical endoluminal deployment system includes an inner catheter or cannula which may also be arranged as a pusher and/or dilator (hereinafter referred to as an inner catheter or catheter element) and a sheath covering the inner catheter. An implant or prosthesis is carried on the inner catheter and is fixed thereto by means of the covering sheath and with or without one or more restraining wires or any of a number of other known retention systems.
The implant or prosthesis might be a stent, a stent graft, a filter, an occlusion device or any other implantable device of such a nature.
Once the distal end of the catheter has been positioned inside a patient, typically at the site of the patient's vasculature to be treated, the device is released and deployed in the desired position. The deployment operation involves retracting the covering sheath so as to expose the device to be implanted, which device is then deployed, either by self-expansion or by means of an expansion device such as an inflatable balloon. In the case where the device is also held by restraining wires, these are withdrawn, typically after retraction of the sheath. Restraining wires may or may not be used in such apparatus, generally dependent upon the nature of the device to be deployed, size restrictions and the particular medical application or intervention procedure.
In order to position a catheter at the site of the patient's vasculature to be treated, a guide wire is first inserted through the vasculature, for example, via the femoral artery. Once the guide wire is in position, a dimensioning catheter is passed over the guide wire to the site of treatment. The dimensioning catheter is provided with a plurality of gold marker bands and is used to determine the length of the vasculature that requires treatment. Once this has been determined, the dimensioning catheter is removed. The appropriate implant is then selected and delivered using a second catheter that is passed over the same guide wire. Typically, the positioning of the implant is achieved with X-ray analysis during the procedure.